1. Field of the Invention
Embodiments of the present invention generally relate to methods for repairing and lowering the dielectric constant of low k films for semiconductor fabrication.
2. Description of the Related Art
The dielectric constant (k) of dielectric films in semiconductor fabrication is continually decreasing as device scaling continues. Minimizing integration damage on low dielectric constant (low k) films is important to be able to continue decreasing feature sizes. However, as feature sizes shrink, improvement in the resistive capacitance and reliability of dielectric films becomes a serious challenge.
Current techniques for the etching or ashing of dielectric films involve process chemistries which create water (H2O) as a byproduct. The water byproduct can be introduced into the deposited dielectric films, thereby increasing the k value of the dielectric film. Also, current techniques for the removal of copper oxides (CuO) and chemical mechanical planarization (CMP) residues involve the use of ammonia (NH3) or hydrogen (H2) plasmas. Removal of the copper oxides and CMP residues are necessary to improve the electromigration (EM) of the metallization structures and the time dependent dielectric breakdown (TDDB) of the ILD films. However, exposing low k films to NH3 and H2 plasmas modifies the film structure and increases the k value. Present repair techniques involve liquid phase silylation or use of supercritical CO2. However, such techniques have not proven effective for repairing sidewall damage of recessed features in the films.
Thus, a method for repairing the dielectric films to lower the k value is necessary to improve efficiency and allow for smaller device sizes.